Light emitting diodes (LEDs) and, more particularly, high power LEDs are being used with increasing frequency to replace conventional light bulbs in motor vehicles such as aircraft and automobiles.
In some LED light engines, LEDs may be electrically and/or mechanically connected to a circuit substrate, such as a printed circuit board, using a number of soldered connections. A solder joint may be formed by providing molten solder at each connection to form a solder joint. In some cases, it is desirable to implement a lead-free soldering process. High temperature lead free soldering processes have been traditionally used for attaching surface mount technology (SMT) components to a printed circuit board (PCB) or other circuit substrates. Exposure to high temperature conditions can introduce thermal stress to the LED. Thermal stresses can tend to reduce LED life expectancy and/or light output. With the introduction of heavy copper PCBs and metal core PCBs, higher thermal stresses may be required to achieve adequate solder joints.